Method of producing combustion



Mal-c1114, 1939. E. l.; WIEGAND l-:r Al.

' METHOD op PRoDucING coMusTIoN u L m m L m, Nf MQ 5 Sheets-Sheet 2Filed June 11, 1937 E. L. WIEGAND er AL.

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METHOD fOF PRODUCING COMBUSTION n@ m Sn am MQ MQ v INVENTOR.

ATTORNEY.

March 14, 1939- E. l.. WIEGAND Er AL METHOD OF PIRODCING COMBUSTIONFiled June 11, 1957 y 5 sheets-sheet 3 INVENTQR. @ze M..

ATTORNEY.

E. L, WIEGAND El' AL.

March 14, 1939. 2,150,533

` METHOD oF PRoDUcING coMBUs'TIoN 1937 5 Shee'tSwSheGt 4 Filed June ll v-I INVENTOR. i MQW .M MW

ATTORNEY.

March 14, 1939. E, W|EGANDET AL METHOD 0F PRjoDucING COMBUSTION 5Vslwets--sheet 5 Filed June' 11, 1957 INVENTOR. 7M Mu,

ATTORNEY.

. 50 drawal of Patented Mar. 14, 1939 2,150,533 METHOD OFPRODUCINGCOMBUSTION Edwin L. Wiegand and Oscar R. burgh, Pa.; said Olson assignorOlson, Pitts-- to said Wie- Application June 11, 1937, Serial No.147,679

-z claims.

This invention. relates generally to hightemperature furnaces and moreparticularly to furnaces which are generally known as muille typefurnaces in which the material being treated is maintained out of directcontact with the products of combustion. The specific furnace hereindisclosed is a rotary furnace of the muflle type adapted to have thematerial to be treated fed therethrough continuously. The furnaceconsists generally of a central chamber or retort through which thematerial to be treated is fed and which is surrounded by a combustionchamber which is constructed of suitable refractory .material such assillimanite, aluminum silicate .15 or zirconium refractory material. Theretort is preferably formed of plumbago. The inner wall of thecombustion chamber is lined with refractory material which in turn iscovered with a heat insulating brick and the whole structure is enclosedwithin a metal shell or casing which is rotatably supported on rollerscarried by a base member.v Suitable means are provided for raising andlowering one end of the base member and with it the furnace whichiscarried thereby. Suitable driving means`J are provided which areadjustable for rotating the furnace at various speeds.

One object of the invention i's to provide a method of producing hightemperatures within a 30 furnace which consists in delivering to thefurnace a mixture of gaseous fuel and air at a manifold pressure inexcess of 30 pounds per square inch and mixing with such fuel mixture anapproximately equal volume of air and burning the l35 mixture in thefurnace and withdrawing the burned gases from the furnace at apredetermined rate so as to maintain the desired pressure conditionwithin the furnace.-

Still another object of provide a new and improved method of burning`fuel and heating a furnace of the character described so as to maintaina very high temperature and a maximum concentration of energy in a smallspace so that a large 45 may be treated in a relatively small furnace.

A further object of the invention is to provide a method of heating afurnace which comprises burning-gaseous fuel in the furnace under highpressure and controlling the rate of withthe products of combustion soas t'o the desired pressurel conditions in the maintain furnace.

Further and more limited objects of the invention will appear as thedescription proceeds and by reference to the accompanying drawings theinvention is to amount of material (Cl. S-117.5)

in which Fig. l is a view inside elevation of the furnace and heatingsystem and disclosing the means for pre-mixing the fuel and forexhausting the burned gases from the furnace; Fig. 2 is a verticalsectional view through the furnace; 5 Fig. 3 is a vertical sectionalview on the line 3--3 of Fig. 2; Fig. 4 is a vertical sectional view onthe line 4-4 of Fig. 2; and Fig. 5 is a vertical sectional view on theline 5--5 of Fig. 2.

Referring now to the drawings, the reference 10 character I designatesgenerally the furnace which consists essentially of an outer metalshellV or casing 2 which is preferably cylindrical in shape and which islined with a layer of heat insulating material 2a of considerablethickness 15 such as insulating brick. The combustion chamber proper ispreferably cylindrical in shape and ts within the layer of heatinsulating brick and is formed of suitable refractory material having4 asteep temperature gradient such as sillimanite or aluminum silicate orzirconium refractory material. The wall of the combustion chamber isindicated by the reference character 3. Disposed within the combustionchamber, preferablyl in concentric relation therewith, is a cylindricalretort 4 which is preferably formed of plumbago and which is covered onboth the inside and on the outside with a coating of highly refractorymaterial such as zirconium oxide or thorium oxide or zirconium silicateabout 512 in thickness which serves as a protection against erosion,corrosion and abrasion. The ends of the combustion chamber are closed bya pair of cylindrical plates 5 and 6 which are formed of the samematerial as the walls of the combustion chamber and which have circularopenings therein which receive the opposite ends of the retort 4. A pairof plates 1 and 8 which are formed of heat insulating material fit overthe opposite ends of the furnace and also have openings thereinintowhich the ends of -the retort project. Fitting over the receiving end ofthe retort isa circular plate 9 which has an opening therein and whichis formed of refractory material.- Fitting over the delivery end of theretort is a block i0 of 45 heating refractory material which hasopenings Il therein through which the material may be discharged.Fitting over the opposite ends of the furnace are end plates I2 and i3which are formed of metal and which are secured to -the outer metalshell 2 by means of suitable bolts. These end plates are made up of aplurality of sections and are -so positioned as to leave a slight airspace between them and the end plates 1 and 8. respectively.

Disposed adjacent the end block I 0 is a discharge funnel I4 into whichthe material from a conveyor I5. The funnel engages under th'e end plateI2 and is held in place by bolts I6 and Il and a spider I9. Disposedbetween the end plate l0 and the spider I9 is a member 20 which servesto hold the end block HJ in place.

In order to provide properl support for the retort, there are providedfour blocks of refractory material which are indicated by the referencecharacters 2|, 22, 23 and 24- which are rectangular in section and whichare arranged in radial slots provided in the wall of the furnace. Theslots extend entirely through the wall of the furnace and are closed bymetal plates A25, 26, 21 and 28. The inner ends of these supportingblocks are shaped to flt the curvature of the openings 29, 30, 3| and 32which extend through the outer wall thereof, that is, through the reof aplurality of sections which are secured together in any suitable manner.member 31 has'circular openings therein which receive the outer ends ofthe tubular members L 33, 34, 35 and 36, as shown most clearly in Figs.

2 and 5.

In order to Withdraw the burned gases and products of combustion fromthe furnace, therel is provided an exhaust manifold 38 which is made upof a pair of plates 39 and 4I) which are shaped in section, as shownmost clearly in Fig. 2, and A through 4a. ue or lthe like. fIn orderl toheat the combustion chamber 4there an elongated delivery openingdisposed so as to discharge tangentially with respect to the inner wallof the combustion chamber.

A's the fuel is delivered through the air mixer somewhat flaring outlet.

Surrounding the furnace and disposed adjacent theopposite ends thereofare a pair of annular wall and extending .into openings provided in thetires are a plurality of studs 81 and 88. Disposed over the studsrespectively are a plurality of spring clips 90 and 9| which are shownmost clearly in Fig. 3 and serve to permit expansion of the furnace withrespect to the tires.

against the tire and serve torhold the furnace.

against movement toward the delivery end therewhich serves to vary therate of delivery through These rollers bear the retort` of the materialbeing treated. The end'plates for the furnace which are indicated by thereference characters I2 and |3 are made up of a plurality of sectionsand. are bolted together by bolts |04. Each of these plates is providedwith slots |05 and has ribs |06 thereon to allow for contraction andexpansion of the plates. The material to be treated is delivered to thefurnace through a spout |01.

In order to concentrate a great amount of energy and create a hightemperature within the combustion chamber, it is necessary that the fuelbe fed to the furnace at considerable pressure as the twenty-fourburners are designed to burn about 1200 cubic feet of natural gas perhour, the gas containing 1000 B. t. u.s per cubic foot. In order toobtain this result, it is necessary to pre-mix thel fuel so as to obtaina fuel mixture containing one part gas to about five parts air and toadmix with each volume of the mixture at the burner air mixer an equalvolume of air which will give a fuel mixture at each burner containingone part gas and about eleven parts air.

The apparatus for pre-mixing the fuel consists of a gas pump |00 fromwhich leads a pipe |09 which delivers gas into an inspirator ||0 at apressure of about 15 to 80 pounds per square inch. -Natural gas isdelivered to the gas pump through a fuel pipe |08. By means of an aircompresser airis pumped through a pipe ||2 into the inspirator ||0 at apressure of about |00 pounds per square inch. The reference charac'-ters H3, ||4 indicate gauges for determining the pressure of gas andair. Suitable control valves ||5 and H6 are provided for regulating thedelivery of gas and air. Leading from the inspirator ||0 is a pipe ||1which connects with a T ||8 from which leads a pipe H9 which connectswith a T |20 to which is connected the fuel supply pipe 84. The fuelmixture delivered to the pipe 84 contains about one part gas to fiveparts air which is delivered to the burners at a pressure between 90 and95 pounds per square inch where an equal volume of air is admixedtherewith.

In order to provide means for preheating the fuel mixture when desiredthere is provided a pipe |2| which leads through the outlet from theexhausting mechanism and. thence into the T |20. Disposed in the pipe|2| is a hand operated valve |22 and disposed in the pipe ||9 is a handoperated valve |23 which may be operated y to deliver the fuel throughthe outlet from the exhaust manifold when and if desired. Should it bedesired to preheat the air which is delivered into the burner airmixers, 'the furnace is provided with a pair. of shells |24 and |25which are detachably secured over the furnace and over the burnerstherefor so that the air which is inspirated into the burner air mixersheated, if desired. f

Operation In the operation of the furnace, power is supw plied to theshaft 91 to rotate the combustion chamber and with it the retort whichis supported therein. Fuel of the proper mixture is delivered to themain manifold 6| through the fuel supply pipe 84. An approximately equalvolume of air is admixed with the fuel at the air mixerfor each burner.The fuel is delivered to each burner at a pressure of to 100 pounds persquare The fuel mixture is ignited at any suitable manner. Due to thedesign, shape may be inch. the burners in and surface area of the burnertunnels, combustion normally takes place in the combustion zone of theburner tunnels and in designing the burner tunnels it is necessary totake into consideration the rate of llame propagation of the particularmixture of fuel, premature kindling, the type of refractory used in theconstruction of the combustion chamber, and the velocity and pressure atwhich the gas is delivered to the burner tunnels in order to keep theflame from flashing or burning back too close to the burner and in orderto maintain the flame and combustion within a well defined area in theburner tunnels. The adjustable legs on the furnace are adjusted so thatthe retort has the proper angle of inclination to maintain the propercharge of material inthe retort at all times so that the material beingtreated will be delivered from the furnace at the desired temperature.However, this angle may be varied depending upon the nature and nace orby varying both,.the time of the heating cycle and the temperature ofthe material delivered from the furnace may be regulated and oontrolled. The material to be treated is fed to the furnace by anysuitable feeding 'mechanism which should be adjustable to vary the rateat which the material' is fed into the furnace. With all of the burnersin operation, it is possible to obtain a temperature in the combustionchamber of approximately 3000 F. without preheating the fuel. Under suchconditions, the temperature within the retort will be between 2100 F.and 2500 F., depending upon the rate of delivery of the material throughthe retort.

With a furnace constructed and operated as herein described, it ispossible to concentrate a very great amount of energy within a smallcombustion space and at the same time treat a very large amount ofmaterial per hour and maintain the maximum temperature desired. If thefuel is preheated, higher temperatures and efhciency can be attainedwith the same fuel pressure and velocity. The speed of the blower whichexhausts the products yof combustion from the furnace may be varied soas to maintain the desired pressure condition in the combustion chamber.

It will now be clear that theheating system and apparatus hereindisclosed will accomplish the objects of the invention as hereinbeforestated. It is, Aof course, to be understood that the embodiment of theinvention herein disclosed is to be considered merely as illustrativeand not in a limiting sense as various changes and modifications may bemade in the details of construction, arrangement and design of parts,without departing from the spirit of the invention. For example, in somecases, it may be necessary to 4provide a plurality of exhaust manifoldsdisposed intermediate the ends of the furnace which would draw equallyfrom both sides so as to maintain substantially uniform conditionsthroughout the combustion chamber. In some cases it may also be'desirable to provide automatic temperature control for the furnace inaddition to'the control of the rate of the work being done and thiscontrol may be arranged to respond to conditions Within the retort orwithin the combustion chamber or within both. The furnace is suitablefor heat treating uniform or non-uniform material/ of various qualitiesand` kinds. The plug which closes one end of the retort may be removableto permit the mechanical removal of fritted ma- 75 terial in case thematerial being treated is subject to' fritting. l

The invention is therefore limited only in accordance with the scope ofthe appended claims.

This application is a companion `case to our copending applicationSerial No. 147,678, iiled June 1l, 1937.

Having thus described our invention, what we claim is:

1. The method of producingcombustion which consists in premixing air andfuel gas, the air being delivered at a pressure of about one hundredpounds per square inch, and the gas being deliveredat a pressure ofabout eighty pounds per square inch, delivering such fuel mixture to aburner at a pressure of about ninety pounds per square inch,.entrainingin said nal mixture anV pressure than vthe gas, to a burner withoutmadelivered at a higher delivering such mixture terially additional air,discharging the nal mixture from the burner at Ahigh velocity andburning the same.

EDWINXL. WIEGAND. OSCAR R. OLSON.

